onclick function callback has no x axis information (category)

Is there anyway to retrieve the x axis category when click on a point or in a bar?

For example, when I add next code to this category chart (http://c3js.org/samples/categorized.html), object d only has the index of x tick but no category name.

``` javascript
selection: {
enabled:true
},
onselected: function(d, element) {
console.log(d);
}
```

I obtain this:
_Object {**x: 1**, value: 200, id: "data1", index: 1, name: "data1"}_
and i want this
_Object {**x: cat2**, value: 200, id: "data1", index: 1, name: "data1"}_

The same info that tooltip shows on mouse over